Devices for mechanically removing particles from liquid are employed in a wide variety of fields and there have been developed innumerable types of filters for this purpose. Commonly, filters are formed by some sort of apertured container filled with a filtering material that defines a large plurality of restricted passages therethrough. Filter materials vary from diatomaceous earth to paper and all serve to mechanically strain or filter particles from a fluid flowing therethrough.
Filters for liquids are normally inserted in or employed in fluid flow systems wherein a pump forces the fluid through the system and many of these applications employ a suction pump so that the fluid is clean before passage through the pump in order to prevent fouling of the pump. It is conventional to employ centrifugal pumps in fluid flow systems; however, in situations wherein filters are provided ahead of centrifugal pumps, it is important to ensure a continuous flow of fluid through the filter to the pump inlet in order to prevent pump runaway and failure. Industrial fluid flow systems operating with centrifugal pumps incorporate appropriate bypass systems to guard against loss of inlet pressure; however, many other systems of relatively low cost and lesser complexity merely depend upon sufficient fluid flow through input filters. This poses a possibility of pump damage under circumstances wherein filter maintenance may be inadequate.
Normal filters are formed with filtering materials inside an apertured container, as noted above. This in itself is disadvantageous for a number of reasons. First, the conditions of the filtering material are not readily visible and thus the material may become clogged or choked with particles or the like without ready notice. Second, cleaning or replacement of the filtering material requires opening a container and removal of the filtering material.
The present invention provides a very simple liquid filter having the filtering material on the exterior thereof for ready visual inspection and easy removal, cleaning and replacement. Additionally, the filter structure hereof readily admits a fluid flow therethrough under conditions of partial or complete clogging of the filtering material.